Electric fuse or cut-out.



PATENTBD DEC. 8, 1903.

L. W. DOWNES.

ELECTRIC FUSE 0R GUT-OUT.

APPLIUATION FILED MAY 7, 1902.

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No. 746,050. PATENTED DEC. 8, 1903. L. W. DOWNBS.

ELECTRIC FUSE 0R GUT-OUT.

APPLICATION FILED MAY '7, 1902.

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PATEN'IED DEC. 8, 1903.

L. w. nowms. ELECTRIC FUSE 0R CUT-OUT.

APPLICATION IILBD MAY 7, 1902.

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UNITED STATES Patented December 8,1908.

PATENT @EETQE.

LOUIS W. DOXVNES, OF PROVIDENCE, RHODE ISLAND, ASSTGNOR TO THE D. 85 W.FUSE COMPANY, OF PROVIDENCE, RHODE ISLAND, A CORPO- RATION OF RHODEISLAND.

ELECETRlC FUSE OR CUT OUT.

SPECIFIGATION forming part of Letters Patent No. 746,050, dated December8, 1903.

Application filed May 7,1902- Seria] llo.106.2'71. (N model.)

To all whom it may concern.-

Be it known that I, LoUIs W. DowNEs, a resident of Providence, Rhodelsland, have invented a new and useful Improvement in Electric Fuses orOut-Outs, which invention is fully set forth n the following specitication.

The improvements constitutingmy present invention are particularlyadvantageous as applied to high-capacity fuses, although parts oftheinvention may be employed to advantage in fuses of low capacity.

The invention will be most readily understood by reference to theaccompanying drawings, which illustrate some of the many possibleembodiments thereof.

Figure 1 is an elevation showing one of my improved fuses mounted incircuit-terminals specially adapted thereto. Figs. 1 and 1 are detailviews of parts of the terminals. Fig. 2 is a longitudinal sectional viewshow ing' the fuse-casing in section and the cartridge-fuse Within thesamein elevation. Fig. 3 is a longitudinal sectional view through thecartridge-fuse of Fig. 2. Fig. at is a transverse sectional view on line4 4 of Fig. 3. Fig. 5 is a sectional elevation, and Figs. 6 and 7sectional views illustrating a cartridgefuse and easing therefor-ofdifferent construction. Figs. 8 and 9 are sectional views illustrating amodified construction of cartridgefuse and casing. Fig. 10 is a section,Fig. 11 a detail, and Fig. 12 an end elevation, showing still anothermodification of the fusecasing and a special terminal therefor. Fig. 13is a section, and Fig. 14 an end view, of a further modification of thefuse-casing. Fig. 15 is an elevation partly in section, and Fig. 16 anenlarged end view of another modified form of casing and terminalstherefor. Fig. 17 is a longitudinal sectional View showing parts of myinvention embodied in a fuse having; an ordinary tubular casing. Figs.18 and 19 are detail views of an improved construction of fuselink. Fig.20 is a detail of a metallic blank; 21, a perspective of said blankafter the wings have been bent, and Fig. 22 a transverse sectional viewpertaining to a modified form of fuse'link.

Referring to Figs. 1 to 4:, A is a base, of

porcelain or the like, upon which the fuse-terminals are mounted. Eachterminal comprises the following parts: a, Fig. 1 is a plate resting onbase A. Upon one end of plate a rests a casting, Fig. 1, comprising asocket b for receiving the end of the circuit-conductor, and an uprightplate I), having a notch 5 extending from its center upward. The castingand plate a are secured to base A by screws 0 c. d d are uprightspring-blades secured to opposite edges of plate a, Fig. 1. E is atubular casino, preferably made of heavy fibrous material and closed atits ends by caps E, each cap having an outwardly-projecting hollowexteriorly-screw-threaded stud 6 thereon. The caps are secured to thetubular part E by screws e. F, 2 and 3, is a cartridgefuse movablyinserted in the casing. It comprises a sheath composed of tube f, ofthin fibrous material, closed at its ends by thin stamped sheet-metalcaps f, which are perforated at f and f to permit the escape of gasesevolved on the blowing of the fuse. The interior construction of thecartridgefuse, including the construction of the fuselink, whichprojects at f f* through the caps ff, will be hereinafter explained.When the cartridge-fuse is in place in the casing, as shown in Fig. 2,the projecting ends f of the fuse-link fit closely and are preferablysoldered or sweated in the hollow studs 6 c 01' caps E E, respectively.The cartridge-fuse is inserted in its casing by removing one of the capsE. After the cap has been replaced and secured the studs 6 e are heatedand touched with solder, which melts and runs into the small spacebetween the projecting ends f f (preferably of heavy tinned copper wire)of the fuse-link and the inner walls of the studs 6 e, uniting them bothmechanically and electrically. The insertion of this inclosedcartridge-fuse into the terminals of a live circuit is facilitated bythe two sets of springblades (Z (Z, which make electrical contact withthe caps E E and temporarily carry the current while the fuse-casing isbeing; adjusted to its final position in the terminals. In this mannerblistering or burning of the contact-surfaces ol": the upright plates Z)and at the ends of the caps E E is prevented.

This is important, because should such blistering or burning occur thecontact area would be so much reduced by the unevenness resulting as tobe inadequate for carrying the current for which the constructionwasdesigned. Aslightburningon thespringblades or at the side of the capsis of no material consequence, and these parts can be replaced at slightexpense should they become seriously damaged by continued use. As it isnot always desirable or reliable to depend upon the spring-blades aloneto carry very heavy currents, owing to the difficulty of gettingsufficient positive contact area, I provide nuts g g, adapted byengagement with the screw-threads on studs 6 e to clamp the end surfacesof the caps E E into tight and positive contact with the inner faces ofup right plates 1) b, respectively, thus relieving the springblades ofthe necessity of carrying any great volume of current. Upon blowing ofthe fuse the nuts are loosened and the casing withdrawn from theterminals, one or both caps E E removed, which is readily accomplished,as the fuse-link has been melted in two at its middle. Sufficient heatis then applied to studs 6 e to melt the solder and permit the ends ofthe fuse-link to be pushed out, leavingthe openings clean and ready forthe insertion of another fuse-linl. This sim ple operation may bereadily carried out by any mechanic orthe engineer of an electricalequipment, and enables large-capacity fuses to be replaced or rechargedat the small eX- pense of the cartridge-fuse, the more expensive casingand fittings being repeatedly reused.

In the construction shown in Figs. 5, 6, and 7 anexteriorly-screw-threaded hollow stud e is secured in an opening in thecenter of each of the thin sheet-metal caps f Fig. '7, which close theends of the thin fibrous tube f of the cartridge-fuse, the metal of thecap being forced into a groove around said stud. The terminals f of thefuse link are soldered in the stud, as before. In conjunction with thisconstruction of cartridge-fuse I prefer to close the ends of the casingA in the manner indicated in Fig. 5. About each end of the tube part ofthe casing is a thin sheet-metal exteriorly-screw-threaded sleevet',which may be secured by indenting it into the outersurface of thetube, as at 'i, by a punch. This sleeve is engaged by a thin sheet-metalscrewthreaded cap 75, Fig. 6, having a central opening 7t, through whichstud 6 projects. As will be apparent, the construction of cartridge-fuseand easing shown in Figs. 5, 6, and 7 may be mounted in terminals suchas shown in Fig. 1 or such as hereinafter described with reference toFigs. 10 and 12.

In another construction shown in Figs. 8 and 9 the stud f is secured ina central opening in each cap f of the cartridge-fuse. In

this instance said studs project inwardly and the terminals f of thefuse-link are soldered in the inner end thereof. A screw 1, passingthrough an opening in the cap of the casing, takes into a screw-threadedsocketinthe stud.

In the modified construction shown in Figs. 10, 11, and 12 thecartridge-fuse is the same as that of Figs. 5 and 7; but theconstruction of the casing is in some respects different.Interiorly-screw-threaded eyelets m, Fig. 11, are forced intocountersunk openings in the tubular part of the casing. A drawn sleeve mof thin metal is then slipped over the end of the casing, so thatopenings therethrong'h register with the openings of the eyelets. Thesleeve is then secured to the eyelets by solder applied through saidopenings. A cap it for closing the end of the casing is then slippedover the sleeve m and secured by screws 0 passing through the caps intothe eyelets. The presence of the eyelets and of sleeve in. prevents wearon the fibrous tubular part of the casing due to repeated removal of thecap it. The terminal for receiving the fuse, as shown in Figs. 10 and12, is the same as that oi. Figs. 1 and 1, except that the socket p forreceiving the end of the circuit conductor or cable is split, so thatthe socket may be contracted to clamp said conductor or cable bytightening a screw 29.

In the modified form of cap Q for the easing, as shown in Figs. 13 and 1the stud (1 is split and adapted to be tightly clamped against theterminals of the fuse-link by tightening screws q, thus avoiding thenecessity of soldering.

In the modified construction of Figs. 15 and 16 the caps R of thefuse-casing have depending spring-blades r r, Fig. 16, at oppositesides. Similar blades 7" "I", projecting upwardly from the terminals,engage tightly between the inner surfaces of blades '1' r and theadjacent surfaces of caps R, thus afford ing a large area of electricalcontact-surface between the fuse-casing and the terminals. The terminalsshown in these figures have no upright contact-plates. A small lug orprojection s on each terminal determines the proper position of the fusewith reference to the spring-blades.

Referring to the interior construction of the cartridge-fuse, as shownin Figs. 3 and 4:, 2 is the fuse-link proper, consisting of a tube ofsuitable metal, preferably of a character capable of being readilyvolatilized with little or minimum disruptive action. Among thepreferred metals I may mention lead, tin, zinc, and alloys thereof. Thetube maybe formed by molding or by bending a piece of sheet metal intoproper form. The wall or walls of the tube are thereby made solid ascontradistinguished from a woven-wire or similarly-formed tube orfuse-link. Openings 3 in tube 2 about its middle reduce the sectionalarea of metal and upon heating of the same cause melting of thefuse-link at this point. 4c 4 are flanged plates or disks fitting withinand closing the tubes 2 a short distance in from the ends thereof,respectively. These plates are soldered to the innor wall of the tube. 55 are fuse-terminals soldered at one end in openings in plates at 4,respectively, and projecting at f f through the caps ff of thecartridge, as already explained. 6 is an envelop of asbestos paper,fitting closely about the fuse-link 2. The space at the middle of thecartridge or sheath and within and about the fuse-link about theasbestos envelop is completely filled with a granular or finely-dividedmaterial 7, such as slaked lime, providing a multitude of intersticesfor the dissipation and escape of the gas evolved by the volatilizalionof the metal of the fuse-link 2 upon blowing of the fuse. The spaces inthe opposite ends of the cartridge (beyond the filling 7) are tightlyfilled. with a packing of asbestos wool 12, which holds the filling 7 inplace and prevents it from jarring and sitting out through ventopeningsff at the same time affording such porosity as to permit the gas toreadily pass therethrough to said vents.

The interior construction of fuse above described, and especially thetubular or hollow fuse-link, is most important in higlrcapacity fuses.As is well understood, and for the reasonsset forth in my Patent No.640,371, dated January 2, 1900, it is desirable as far as possible toreduce the area of cross-section of the metal of the fuse-link to theminimum amount, while at the same time providing a maximum surface areafor conducting the electric current and radiating the heat produced bythe same. Important results follow. The actual bulk or volume of metal(composing the fuse-link) necessary to carry a given current may bereduced. The metal may be so distributed that when it is suddenlyvolatilized by the action of the current the gases can be readilydisposed of or dissipated through the porous filling which surrounds thefuse-link, with consequent reduction of the pressure developed inside ofthe fuse-casing. By the tubular form of fuselink above described Iattain these results to the maximum degree. With a minimum bulk orvolume of metal I obtain a maximum surface of fuse-link exposed to theporous filling, since the filling on the outside as Well as the fillingwithin the cylinder provide paths for the escape of volatilized metalupon blowing of the fuse. In this connection it should be explained thatthe abestos envelop 6 acts simply to direct the gases toward the ends ofthe casing at the instant of volatilization of the metal, and yet doesnot entirely prevent the gases from expanding in a transverse direction,since the envelop is usually broken open upon disruption of the fuse.

While the tubular form of fuse-link of cirlar cross-section is preferredand the most efficient for my purposes, the modified forms shown inFigs. 18,19,220, 21, and 22 have been found to yield good results. InFigs. 18 and 19 the plates-4 4:, to which the fuse-terminals 5 5 arerespectively secured, are connected to two flat metal strips 8 8,reduced at their middle 11 to cause them to melt at that point. In thetubular construction shown in Figs. 20, 21, and 22 four fiat metalstrips 8 are used. In this case the plates to which the fuse-terminalsare secured are formed from metal blanks 9, Fig. 20, the wings 10 ofsaid blank being bent over, as shown in Fig. 21, and the end of stripsof fuse metal soldered thereto. Fig. 22 shows the envelop ofasbestos-paper wrapper about the four-sided fuse-linlz. A similarenvelopis placed about the fuse-link of Figs. 18 and19. These modifiedforms of the fuse-links are filled and surrounded with the granularmaterial in the same manner as shown in Fig. 3.

As will be apparent, the herein-described fuse link and interiorconstruction can be used in conjunction with any suitable form ofinclosing casing. For example, in Fig. 17 I have shown it used inconjunction with the ordinary tubular casing.

What I claim is- 1. In an electric fuse or cut-out, a cartridgefusecomprising an inclosing sheath, a fuselink within said sheath, and afilling of suitable material within the sheath about the fuse-link; acasing in which the cartridge fuseis removably inserted comprising atubular part, removable caps closing the opposite ends of the tubularpart and electrically connected to the terminals of the fuse-link of thecartridge-fuse; and circuit-terminalsinwhich the fuse is mounted makingdirect electrical contact with the caps of the casing.

2. In an electric fuse or cut-out, a cartridgefuse comprising aninclosing sheath, a fuselink within said sheath, and a filling ofsuitable material within the sheath about the fuse-liuk; a casing inwhich the cartridgefuse is removably inserted comprising a tubular part,removable caps closing the opposite ends of the tubular part, andelectrically connected to the terminals of the fuse-link of thecartridge-fuse; and circuit-terminalsin which the fuse is inserted eachhaving spring-blades making electrical contact with the sides of one ofthe caps of the casing and an upright plate bearing with electricalcontact against the exterior surface of the end of said cap.

3. In an electrical fuse or cut-out, a casing comprising a tubular partand caps closing the ends of said tubular part, a fuse-link within thecasing electrically connected between the caps, anexteriorly-screwthreaded stud projecting from each end of the casing,circuit-terminalsin which the fuseis mounted each having an uprightplate through which one of the studs passes, and a nut on theprojet-ting end of each stud for clamping the end surface of each capinto tight electrical contact with the adjacent surface of the uprightplate of the corresponding terminal.

at. In an electric fuse or cutout, a casing comprising a tubular part,caps closing the ends of said tubular part, and a hollow stud projectingfrom each cap; a cartridge-fuse removably inserted in the casingcomprising; a sheath, a fuse-link Within said sheath having terminalsprojecting from the ends of the sheath into the hollow stud and makingelectrical contact therewith, and a filling of suitable material Withinthe sheath and about the fuse-link.

5. In an electric fuse or cut-out, a casing comprising a tubular part,caps closing the ends of said tubular part, and a hollow stud projectingfrom and integral with each cap; a cartridge-fuse removably inserted inthe casing comprising a sheath, a fuse-link Within said sheath havingterminals projecting from the ends of the sheath into the hollow studsand making electrical contact therewith, and a filling of suitablematerial With-- in the sheath and about the fuse-link.

6. In an electric fuse or cut-out, a casing comprising a tubular part,caps closing the ends of said tubular part, and a hollow stud projectingfrom and integral With each cap; a cartridge-fuse removably inserted inthe casing comprising a sheath, a fuse-link within said sheath havingterminals projecting from the ends of the sheath into the hollow studsand soldered therein, and a filling of suitable material within thesheath and about the fuse-link.

7. In an electric fuse, a tubular metallic l'use-link having a solidwall.

8. In an electric fuse, a tubular metallic fuse-link having a solid Wallperforated to cause fusing of the same at a predetermined point.

9. In an electric fuse, a tubular metallic fuselink having a solid Walland a filling of suitable material within and about said link.

10. In an electric fuse, a fuse-link having opposing inner walls, anenvelop of asbestos about the fuse-link, a filling of suitable ma-'terial Within the envelop and betweensaid opposing inner \'-.'alls andabout the fuse-link and its envelop.

11. In an electric l'use, an inclosing casingor sheath havingvent-openings at its ends, a fuse-link Within the casing or sheath, afilling of suitable finely-divided material about the fuse-link, and asuitable porous filling in each end of the casing; preventing thefinelydivided material from sifting through the vent-openings.

in testimony whereof I have signed this specification in the presence oftwo subscribing; witnesses.

LOUIS W. DOWNES.

Witnesses:

JAMES H. THURSTON, EDWIN P. LLLEN.,

